Traders

Traders sell gear, give quests and buy your loot. Each has loyalty levels (LL): reaching one needs a player level, reputation with that trader and an amount spent there. Higher levels sell better gear.

Level Prapor and Therapist first. They hand out most of the early quests, Prapor sells weapons and ammo, and Therapist sells the meds you'll need. Next come Skier, Peacekeeper and Mechanic (weapon parts and the long Gunsmith quest line), then the rest. Some traders only unlock through a quest.